What are the Roman numerals from 1 to 21?

Answer 1

In addition notation: I, II ,III, IIII, V, VI, VII, VIII, VIIII, X, XI, XII, XIII, XIIII, XV, XVI, XVII, XVIII, XVIIII, XX and XXI. In subtractive notation: I, II, III, IV, V, VI, VII, IIX, IX, X, XI, XII, XIII, IXV, XV, XVI, XVII, IIXX, IXX, XX and XXI.